Semmes-Weinstein monofilament testing using a 2.83 or 3.22 filament is used to assess what in carpal tunnel syndrome?

Semmes-Weinstein monofilament testing using a 2.83 or 3.22 filament is used to assess what in carpal tunnel syndrome?

• A. Light touch sensation in the median nerve distribution
• B. Grip strength
• C. Pain sensation to pinprick
• D. Temperature discrimination

Answer: (A)

Semmes-Weinstein monofilaments of 2.83 or 3.22 are used to measure light touch, i.e., protective cutaneous sensation. In carpal tunnel syndrome, the sensory loss typically occurs in the median nerve distribution, so testing with these filaments helps detect diminished light touch in the thumb, index, middle, and radial half of the ring finger. This modality specifically assesses small pressure thresholds on the skin mediated by mechanoreceptors, not motor strength or sharp pain. Grip strength would be tested separately, while pinprick and temperature discrimination evaluate different sensory fibers and are not the primary use of these filaments.

Semmes-Weinstein monofilaments of 2.83 or 3.22 are used to measure light touch, i.e., protective cutaneous sensation. In carpal tunnel syndrome, the sensory loss typically occurs in the median nerve distribution, so testing with these filaments helps detect diminished light touch in the thumb, index, middle, and radial half of the ring finger. This modality specifically assesses small pressure thresholds on the skin mediated by mechanoreceptors, not motor strength or sharp pain. Grip strength would be tested separately, while pinprick and temperature discrimination evaluate different sensory fibers and are not the primary use of these filaments.